On the influence of spin fluctuations on the superconducting transition temperatures of transition metals

Abstract

The authors develop an ab initio theory for the combined influence of phonons and spin fluctuations on the superconducting transition temperatures, Tc, of transition metals. The ingredients of the Eliashberg equations, like the electronic structure, the spin fluctuation spectrum and the coupling function, are calculated in the local density functional-random phase approximation without introducing adjustable parameters, whereas the spin-independent part of the Coulomb interaction is treated using a McMillan parameter. They describe the steps involved in transforming the Eliashberg equations into a numerically tractable form without resorting to jellium model-like assumptions. For the case of vanadium they find that spin fluctuations reduce Tc substantially below the value corresponding to the pure phonon mechanism.